我不是很熟悉Android的SQLite数据库。我只有填充SQLite数据库的大概的了解。我按照一些教程，但他们告诉不同的东西。 我有一个Android项目和它的packeges之一是名为.db 该套件包括5个不同的类别。它们是：
I am not very much familiar with android sqlite database. I only have rough idea of populating sqlite database. I have followed some tutorials but they tells different things. I have an android project and one of its' packeges is a .db This package consists of 5 different classes. They are:
我知道SelectDBAdapter类是用来选择数据库中的数据。我的数据库是这是.JPEG format.I可以从sqliteBrowser打开资源文件夹。 其实，我想知道的是为什么要使用这些不同的类？什么是每个类的目的是什么？
I know SelectDBAdapter class is used to select data from the database. My database is in asset folder which is in .jpeg format.I can open it from sqliteBrowser. Actually, what I want to know is why should we use these different classes ? and what's the purpose of each and every class ?
我真的很抱歉，我不能发表codeS，因为这个项目是属于另外一个人（我的朋友）。 我将非常感谢，如果有人可以这么好心足以说明使用这些不同类别的含义，我们为什么要使用这样的塞纳里奥？
I am really sorry, I cannot post codes since this projects belongs to another person (my friend). I would be much obliged if anyone could be so kind enough to explain the meaning of using these different classes and why should we use such a senario ?
推荐答案从我的开发经验，我总是preFER在/ RES加prepared SQLite数据库文件/原folder.You创建/管理使用Firefox的SQLite的经理插件SQLite数据库，这是一个伟大的工具。这种方法实在是太棒了，因为
From my development experience , I always prefer to add a prepared sqlite database file in the /res/raw folder.You create/manage sqlite database using Sqlite Manager addon of Firefox , it's a great tool. This method is really great because
- 首先，我并不需要写C $ CS一堆$创建/管理数据库。
- 最重要的是，一些应用程序需要从pre-填充数据库中读取。我并不需要关心什么应用程序需要和数据库是否为空或者已经填满。它为所有的目的。我只需要编写的软件运行所需要的sql语句简单一些的方法。
下面是我自己的定制DatabaseHelper类。要使用这个类，你需要遵循一些指示。
Here is my own customised DatabaseHelper class. To use this class you'll need to follow some instructions.
编辑包名，并在下面的类你的数据库文件名。
Edit the package name and your db file names in the following class. package your.packagee.name; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import android.content.Context; import android.content.res.Resources; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteException; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; import android.widget.Toast; public class DataBaseHelper extends SQLiteOpenHelper { private static final String pkg = "your package name"; private static String DB_PATH = "/data/data/" + pkg + "/databases/"; private static String DB_NAME = "yourDBFile.sqlite"; int[] dbfiles = { R.raw.chunk1 , R.raw.chunk2 ..... }; private SQLiteDatabase myDataBase; private final Context myContext; public DataBaseHelper(Context context) { super(context, DB_NAME, null, 1); this.myContext = context; } public void createDataBase() { boolean dbExist = checkDataBase(); if (dbExist) { // do nothing - database already exist } else { this.getReadableDatabase(); try { CopyDataBase(); } catch (IOException e) { Toast.makeText(myContext, e.getMessage(), Toast.LENGTH_SHORT) .show(); Log.d("Create DB", e.getMessage()); } } } private boolean checkDataBase() { SQLiteDatabase checkDB = null; try { String myPath = DB_PATH + DB_NAME; checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS); } catch (SQLiteException e) { Toast.makeText(myContext, e.getMessage(), Toast.LENGTH_SHORT) .show(); Log.d("Check DB", e.getMessage()); } if (checkDB != null) { checkDB.close(); } return checkDB != null ? true : false; } private void CopyDataBase() throws IOException { InputStream databaseInput = null; Resources resources = myContext.getResources(); String outFileName = DB_PATH + DB_NAME; OutputStream databaseOutput = new FileOutputStream(outFileName); byte[] buffer = new byte[512]; int length; for (int i = 0; i < dbfiles.length; i++) { databaseInput = resources.openRawResource(dbfiles[i]); while ((length = databaseInput.read(buffer)) > 0) { databaseOutput.write(buffer, 0, length); databaseOutput.flush(); } databaseInput.close(); } databaseOutput.flush(); databaseOutput.close(); } public void openDataBase() throws SQLException { String myPath = DB_PATH + DB_NAME; myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS); } @Override public synchronized void close() { if (myDataBase != null) myDataBase.close(); super.close(); } @Override public void onCreate(SQLiteDatabase db) { } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { } public boolean deleteItem (String ID){ String query = "delete from item where id='" + ID + "'" ; Log.d("Query : ", query); try{ myDataBase.execSQL(query); return true ; } catch (Exception e){ Log.d("Exception", e.toString()); return false ; } } public Cursor getSearchFromID(String id) { return myDataBase.rawQuery("select * from item where id = \"" + id + "\"", null); } public boolean addSave(String type, String data , String time) { String query = "insert into item (type, data , timestamp) values ('" + type + "', '" + data + "', '" + time + "')"; try { myDataBase.execSQL(query); return true ; } catch (Exception e) { return false ; } } }
下面是写为样本，如何使用它的一些方法。
Here's some methods written as a sample , how to use it.
用法很简单。当你的应用程序启动，这意味着在你的启动活动中使用这种code初始化数据库
Usage is simple. When your application starts , that means in your Launcher activity use this code to initialize your database
DataBaseHelper helper = new DataBaseHelper(this); helper.createDataBase(); helper.openDataBase(); helper.close();
就用写在DatabaseHelper类中的方法。样本会是这样
Then just use the methods written in DatabaseHelper class. A sample will be like this
String id = "1"; DataBaseHelper helper = new DataBaseHelper(this); helper.openDataBase(); Cursor c = helper.getSearchFromID(id); if(c.getCount() > 0){ c.moveToFirst(); while(!c.isAfterLast()){ // extract your data from cursor c.MoveToNext(); } }
希望这本书能解决你的所有关于Android的SQLite数据库的问题。至少它解决了我。谢谢你。
Hope it will solve your all problems about sqlite database in Android. At least it solved for me. Thank you.
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